A bomb packed with nails exploded in a crowded Christian market selling pork ahead of New Year celebrations in eastern Indonesia on Saturday, killing seven people and wounding 53, police said.
The blast in Palu, capital of volatile Central Sulawesi province, came after warnings of militant violence during the Christmas and New Year season in Indonesia.
Indonesia is the world's most populous Muslim nation. Pork is forbidden to Muslims, who account for some 85 percent of the people, but eastern Indonesia has large pockets of Christians.
Bystanders carried bloodied shoppers from the makeshift market to a road, putting them in passing cars to be taken to hospital. One man screamed as he held up his bloodied arms.
The official Antara news agency said another bomb was found and defused near the market in Palu, 1,650 km (1,030 miles) northeast of Jakarta.
Material like timers and cables were found in packages at two other sites in Indonesia on Saturday, but they did not include explosive materials, Purwoko said.
Central Sulawesi is a region plagued by religious violence and tension since the late 1990s. Fighting between Muslims and Christians from 1998-2001 killed 2,000 people, mainly around the Muslim town of Poso.
Indonesian President Susilo Bambang Yudhoyono condemned the Palu blast and ordered an investigation, his spokesman said.
The explosion occurred not long after dawn when people were shopping. Slabs of pork were still sitting on wooden tables inside the small market, which local police said was only used ahead of special occasions.